802.11 is a standard of wireless local area network formulated by IEEE (Institute of Electrical and Electronics Engineers, Institute of Electrical and Electronics Engineers), which is mainly used for solving wireless access of users and user terminals in a local area network of an office and a campus network.
The IEEE 802.11 technology is configured to formulate a universal MAC (Medium Access Control, medium access control) layer for a plurality of PHYs (Physical Layer, physical layer) to standardize the construction of the wireless local area network. A main task of the medium access control layer MAC is to establish an addressing and channel access control mechanism for multiple stations in a same network, so as to make communications between the multiple stations possible.
A basic component of WLAN (Wireless Local Area Networks, Wireless Local Area Networks) is a BSS (Basic Service Set, basic service set), which consists based on stations STA having certain association within a particular coverage area, such as, a BSS2 and a BSS3 as shown in FIG. 1. In a BSS network, a central station performing a full-time management on a BSS is called as an AP (Access Point, access point), and other stations STA in the network are associated with it. A plurality of BSS networks are mutually connected through a DS to form an ESS (Extended Service Set, extended service set). In the absence of the AP, the stations STA may also directly communicate with each other with a self organized network, and the network is an independent BSS or IBSS, such as BSS1 as shown in FIG. 1.
NAN (Neighborhood Area Network, neighborhood area network) is a project group established by WFA in December, 2011, which commits itself to, under the condition of low energy consumption in a pre-association state, mutual information acquisition between wireless devices in a direct connection manner without the assistance of a relay device (such as AP, base station or the like). It has the following three requirements: 1. a low power consumption (energy saving); 2. direct connection without a relay device; and 3. in a Pre-Association state (only Class 1 information can be sent). The Class 1 information carries a Control Frame (a control frame), Management frames (a management frame) and Data frames (a data frame).
In the NAN technology, the discovery between stations is mainly achieved by broadcasting a beacon frame. Namely, a station, on a certain channel, periodically broadcast sends, in accordance with a certain beacon frame sending period (the value range is 20 ms to 1000 ms and the preset value is 100 ms), a beacon frame carrying its own information using a random event as a starting point. A surrounding station thereof learns about the existence of the station and the information of the station by receiving and interpreting information of the broadcast beacon frame.
An MAC address, also called a hardware address, is configured to define the location of a network device, which consists based on a 48-bit long hexadecimal number, 0-23 digits are an organization unique identifier, which is a mark for identifying a node of a local area network node. 24-47 digits are self-assigned by a manufacturer of the network device. The format of a data packet is as shown in table 1:
TABLE 1
Wherein, a field of Address 1 field is filled with an immediate receiving address of the frame, a field of Address 2 is filled with an immediate sending address of the frame, and a field of Frame Body is loaded with an upper layer content to be transmitted through an MAC packet (such as an IP packet). An MAC addresse is a unique identifier of a station within the scope of communication of an MAC layer. Therefore, when monitoring a beacon frame carrying a certain MAC address in a channel, the surrounding station may determine there exists, in the neighborhood, a station corresponding to the MAC address.
A beacon frame broadcasted by each station may be received by any station around. Since a station could not encrypt a beacon frame broadcasted by itself as no key negotiation is implemented between stations at a Pre-Association (pre-association) state, a beacon frame broadcasted by each station may be interpreted by any station around, and an MAC address information of itself carried in the beacon frame may also be achieved by any station around. The disclosure of the MAC address information will make privacy of a user of each station unprotected.